Skype's co-founder Niklas Zennstrom has handed over his CEO title as parent eBay expressed disappointment over the unit’s performance.

Zennstrom will become a non-executive chairman of the board of directors of Skype, while Michael van Swaaij, eBay's chief strategy officer, is stepping in as interim CEO until a permanent replacement is hired, eBay announced Monday.

EBay acquired VoIP provider Skype in October 2005 for approximately $2.6 billion, plus an optional amount dependent on the achievement of certain goals. From the start, many have questioned the logic behind the acquisition, suggesting that eBay would have a difficult time recouping its investment and leveraging Skype to boost interactions with eBay among buyers and sellers.

In the second quarter, ended June 30, Skype's net revenue hit $90 million, up 103 percent compared with the same quarter in 2006. Meanwhile, registered user accounts grew 94 percent to 220 million.

However, eBay CEO and president Meg Whitman, discussing the second quarter's financial results in a conference call in July, said that, despite its revenue and user growth, Skype hasn't achieved the desired level of "user activity."

In August, Skype suffered a widely publicised and embarrassing outage that lasted about two days and left millions of users fuming worldwide and many openly questioning the stability of Skype's technical platform.

Durzy acknowledged that eBay is disappointed that Skype hasn't performed as well as expected in the short term in the areas of user activity and monetisation, but the company believes Skype is still a very valuable asset.

Based on reporting by Juan Carlos Perez, IDG News Service.